1. Field of the Invention
The present invention relates to an operating device for a hollow drill and including a housing, a drill receiving chuck supported in the housing for rotation relative to the housing, a drive unit for rotating the drill, and a bottom element adjoining the chuck at side of the chuck facing in a direction opposite to the drilling direction.
2. Description of the Prior Art
German Utility Model No. 1,898,626 discloses a drill receiving chuck in which a hollow drill is form-lockingly secured. The chuck has a blind bore with a projection radially extending from an inner wall of the blind bore. The bottom of the blind bore forms the bottom element. The hollow drill has, in its outer surface a groove inclined partially to the longitudinal axis of the hollow drill.
For connecting the hollow drill with the drill chuck, they are fitted together and rotated in opposite direction until a free end of the hollow drill, which faces in a direction opposite to the drilling direction abuts the bottom of the blind bore which faces in the drilling direction. The hollow drill is used for forming bores in hardened structural components for anchors and for forming passages for tubular conduits. During formation of such bores and passages, drilling cores are formed in the hollow drill which should be from time-to-time from the hollow drill. The hollow drill is provided in its end facing in the drilling direction with cutting means which projects radially inward of both sides of the support body of the hollow drill. Because the outer diameter of a drilling core substantially corresponds to the inner diameter of the bore formed by the cutting means but is smaller than the inner diameter of the tubular support body of the hollow drill, the removal of the drilling core from the hollow drill from the end of the support body of the drill, which lies opposite to the cutting means, can be easily done.
In order to be able to remove the drilling core from the hollow drill in an above-described manner, it is necessary to separate the hollow drill and the chuck. This process is very time - consuming. In addition, use of special tools is required for gripping the support body in order to be able to rotate it relative to the chuck. Moreover, after an extensive drilling, the hollow drill becomes so hot that extraction of the released drill from the chuck with bare hands is not possible.
Accordingly, an object of the invention is to provide an operating device for a hollow drill which would insure quick, reliable and easy removal of a drilling core from the hollow drill in the direction opposite to the drilling direction, without the necessity to extract the hollow drill from the chuck which is secured in the operating device.